Abstract

Most familiar odours are complex mixtures of volatile molecules which the olfactory system automatically synthesises into a perceptual whole. However, odours are rarely encountered in isolation, thus the brain must also separate distinct odour objects from complex and variable backgrounds. In vision, autistic traits are associated with superior performance in tasks that require focus on the local features of a perceptual scene. The aim of the present study was to determine whether the same advantage was observed in the analysis of olfactory scenes. To do this, we compared the ability of (i) Forty young adults (aged 16-35) with high (n=20) and low levels of autistic traits and, (ii) Twenty children (aged 7-11), with (n=10) and without an autism spectrum disorder diagnosis, to identify individual odour objects presented within odour mixtures. First, we used a 4-alternative forced choice task to confirm both adults and children were able to reliably identify eight blended fragrances, representing food related odours, when presented individually. We then used the same forced-choice format to test participants' ability to identify the odours when they were combined in either binary or ternary mixtures. Adults with high levels of autistic traits showed superior performance on binary but not ternary mixture trials. While children with an autism spectrum disorder diagnosis outperformed age matched neurotypical peers, irrespective of mixture complexity. These findings indicate, the local processing advantages associated with high levels of autistic traits in visual tasks are also apparent in a task requiring analytical processing of odour mixtures.